1. Field of the Invention
The present invention relates to frequency selective circuits, and in particular, to frequency selective circuits used for emphasizing higher frequency signal components of a signal for purposes of peaking selective ranges of signal frequencies.
2. Description of the Related Art
In many signal processing applications it is desirable to provide high frequency compensation in the form of emphasizing higher frequency signal components over lower signal components. For example, one of many such applications includes circuits used for processing video display information, such as text and images. In such applications, it is often desirable to add high frequency signal emphasis so as to cause the video information to appear more visually sharp on the display device (e.g., cathode ray tube or liquid crystal display).
For television signal applications, such signal emphasis or boosting, is often introduced at a frequency approximating that of the chrominance signal carrier of the television signal, the absolute frequency of which will vary according to the television signal standard in use. With the increased use of high definition televisions and personal computers for displaying such images, the displays of such images must occur at higher frequencies due to the increased horizontal scan rates of such devices.
Accordingly, with a potentially large number of applications available for such a circuit, in terms of needing to provide high frequency signal emphasis at a number of various frequencies, it would be desirable to make such high frequency emphasis adjustable so that the user can alter the emphasis to accommodate the scan rate of the display device.
A signal peaking circuit in accordance with the presently claimed invention selectively emphasizes the higher frequency signal components of an incoming signal. Control circuitry is included to allow the number and peak values of the emphasized signal components to be selectively variable.
In accordance with one embodiment of the presently claimed invention, an apparatus includes a signal peaking circuit for selectively increasing high frequency components of a digital signal including an input signal terminal, signal peaking circuitry and signal combining circuitry. The input signal terminal conveys an input signal with a plurality of lower frequency signal components and a plurality of higher frequency signal components. The signal peaking circuitry, coupled to the input signal terminal, receives the input signal and selectively emphasizes the plurality of higher frequency signal components over the plurality of lower frequency signal components to provide an emphasized signal. The signal combining circuitry, coupled to the input signal terminal and the signal peaking circuitry, receives and selectively combines the input signal and the emphasized signal to provide a plurality of output signals, wherein each one of the plurality of output signals corresponds to the input signal and includes a respective selected portion of the plurality of higher frequency signal components emphasized over the plurality of lower frequency signal components and a respective selected peak signal value.
In accordance with another embodiment of the presently claimed invention, an apparatus includes a signal peaking circuit for selectively increasing high frequency components of a digital signal including input signal means, signal peaking means and signal combiner means. The input signal means is for conveying an input signal with a plurality of lower frequency signal components and a plurality of higher frequency signal components. The signal peaking means is for receiving the input signal and selectively emphasizing the plurality of higher frequency signal components over the plurality of lower frequency signal components and providing an emphasized signal. The signal combining means is for receiving and selectively combining the input signal and the emphasized signal and providing a plurality of output signals, wherein each one of the plurality of output signals corresponds to the input signal and includes a respective selected portion of the plurality of higher frequency signal components emphasized over the plurality of lower frequency signal components and a respective selected peak signal value.
In accordance with still another embodiment of the presently claimed invention, a signal peaking method for selectively increasing high frequency components of a digital signal includes:
receiving an input signal with a plurality of lower frequency signal components and a plurality of higher frequency signal components;
processing said input signal by selectively emphasizing the plurality of higher frequency signal components over the plurality of lower frequency signal components and providing an emphasized signal; and
selectively combining the input signal and the second filtered signal and providing a plurality of output signals, wherein each one of the plurality of output signals corresponds to the input signal and includes a respective selected portion of the plurality of higher frequency signal components emphasized over the plurality of lower frequency signal components and a respective selected peak signal value.